The U.S. Department of Justice has issued guidelines to limit the routine practice of ordering cloud computing companies to not tell customers that the government has a search warrant for their email and data. The policy change is a legal victory for Microsoft, which went to federal court to broadly challenge the use of secrecy orders the tech giant reasons were meant to be used rarely.

"This is an important step for both privacy and free expression," Microsoft president and chief legal officer Brad Smith wrote in a blog post Monday. "It is an unequivocal win for our customers, and we’re pleased the DOJ has taken these steps to protect the constitutional rights of all Americans."

Cloud computing has created a legal gray zone that Microsoft alleged the government has abused to conduct constitutionally questionable searches and impose restrictions on speech. In pre-internet times, the person or business on the unhappy end of a search warrant would know that they have been searched, even if they only learned about it after the fact when told by a neighbor or landlord.

These days what investigators seek is often documents and emails stored on cloud servers. These allows them to serve the warrant on the cloud storage vendor, often with an accompanying order that they not inform their customers. Microsoft argued the secrecy orders, allowed under an elastic reading of the Electronic Communications Privacy Act of 1986, violated its First Amendment right to communicate freely with customers and the customers' Fourth Amendment right to freedom from unreasonable search and seizure.

Prior to filing suit in April 2016, Microsoft documented 2,576 cases in which the government obtained a court order prohibiting the company from telling the customer their data had been searched. In 68 percent of the cases the gag order had no expiration date. "This means that we effectively are prohibited forever from telling our customers that the government has obtained their data," Smith wrote at the time.